摘要:

An acute toxicity curve for dissolved ozone (O3) in soft water at 10 °C, using 10–13-cm rainbow trout (Salmo gairdneri) as the test species was calculated. The 96-h LC50 (95%, confidence interval) was 9.3 (8.1–10.6) μg/L. The lethal threshold level was about 8 μg/L mandating that a conservative margin of safety be used if ozone is employed as a fish disease control agent. Death apparently results from massive destruction of the gill lamellar epithelium together with a severe hydromineral imbalance. In partial chronic (3-mo) testing, 2 μg/L caused no significant biological damage while 5 μg/L caused some gill pathological changes and reduced feeding behavior. Accordingly, 2 μg/L is suggested as a provisional maximum safe exposure level, pending completion of life cycle studies. Thus, if ozone-treated water is discharged into the environment, dissolved O3should be reduced to at least the 2 μg/L level to minimize adverse impacts on salmonids in receiving waters.Key words: ozone, fish toxicity, acute ozone toxicity, chronic ozone toxicity,Salmo gairdneri

ISSN:0706-652X    

DOI:10.1139/f79-088

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The influence of salinity on mortality in mummichogs,Fundulus heteroclitus, subjected to naphthalene and the physiological bases for the salinity-dependent mortalities were determined. Fish were acclimated to five salinities, 2, 8, 15, 23, and 33‰, and exposed to 6 and 4 mg naphthalene/L. At 4 mg/L, fish survival was greater at hypo- and near isoosmotic (15‰) salinities than at hyperosmotic salinities. At 6 mg/L, survival was generally greatest at 8 and 15‰ and decreased at the salinity extremes. In fish exposed to 4 mg naphthalene/L, uptake was more rapid at the iso- and hyperosmotic salinities than at hypoosmotic salinities and osmotic imbalance occurred only at hyperosmotic salinities. Serum cortisol levels and oxygen consumption rates increased at all salinities upon exposure to 4 mg naphthalene/L. However, the most significant increases in oxygen consumption rates occurred at hyperosmotic salinities. Thus, the greater naphthalene uptake, osmotic imbalance, and metabolic stress occurring at hyperosmotic salinities may contribute to the increased mortality of naphthalene-exposed fish acclimated to hyperosmotic salinities.Key words: toxicity, naphthalene, petroleum hydrocarbon, teleost,Fundulus heteroclitus, salinity, osmoregulation, uptake, oxygen consumption, stress

ISSN:0706-652X    

DOI:10.1139/f79-089

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Acute ammonia toxicity in rainbow trout (Salmo gairdneri) was studied by intraarterial injection of NH4Cl and NH4HCO3. Hydrogen ion and total ammonia concentrations were measured in blood sampled from the dorsal aorta both before and after injection. Although injection of NH4HCO3increased arterial blood pH, and injection of NH4Cl decreased arterial blood pH, the same dose of each was required to kill fish. While the un-ionized form of ammonia in water has been shown to be toxic, in the blood either the ionized form or the total ammonia load is toxic to fish. Ammonia levels were measured in pre- and postbranchial blood. Mean values were not significantly different, but paired values indicated a fall in blood ammonia due to excretion across the gills. There appears to be a more rapid excretion of ammonia following NH4HCO3infusions, which result in higher un-ionized ammonia levels in blood compared with those following NH4Cl infusions. These results are consistent with the hypothesis that ammonia is excreted in the un-ionized form.Key words: un-ionized ammonia, ionized ammonia, gills, pH, blood

ISSN:0706-652X    

DOI:10.1139/f79-090

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Yellowstone cutthroat trout (Salmo clarki bouvieri) have 64 chromosomes, without any subtelocentric chromosomes, while west-slope cutthroat trout (S.c.lewisi) have 66 chromosomes, including 12 subtelocentrics. Both subspecies have 104 chromosome arms. Chromosomal similarities are apparent between the Yellowstone cutthroat and Great Basin cutthroat subspecies, and between west-slope cutthroat trout and coastal cutthroat trout. These results demonstrate that at least two distinct evolutionary lines of cutthroat trout are present in the northern Rocky Mountain region.Key words:Salmo clarki, karyotypes, Yellowstone cutthroat trout, west-slope cutthroat trout, evolutionary relationships

ISSN:0706-652X    

DOI:10.1139/f79-091

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Rainbow trout (Salmo gairdneri) were exposed to the O-antigen ofYersinia ruckeriby various immunization regimens. The passive hemolytic plaque assay was used to show specific splenic plaque-forming cells (PFC) and passive hemagglutination demonstrated humoral antibody titers in fish injected with or immersed in the antigen preparations. Preceding antigen immersion with a 2-min immersion in either a 5.2 or a 2.6% NaCl solution did not affect the numbers of PFC or levels of antibody. Fish held for 2 min in ethylm-aminobenzoate methanesulfonate (MS-222®) before antigen immersion showed no significant difference from the control fish. Dosage studies showed that the minimal concentration of antigen for induction of PFC by immersion was 5.0 μg/mL.Key words: plaque-forming cells, immunization, rainbow trout immersion,Yersinia ruckeri

ISSN:0706-652X    

DOI:10.1139/f79-092

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The snow pack that accumulated in central Ontario in the winter of 1977–78 had a pH of 4.0–4.5. The resultant runoff in the following spring in three intensively studied watersheds was characterized by a 2–13-fold increase in H+content. Between 36 and 77% of the year's export of H+from the watersheds occurred in April. Similar pH depressions were observed in almost all of 17 other streams that were less frequently sampled and in the littoral zones, surface waters, and outflows of five lakes.Key words: acidification, snowmelt, hydrogen ion

ISSN:0706-652X    

DOI:10.1139/f79-093

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

An age-structure model that incorporates recent information regarding growth and reproduction has been developed to investigate the dynamics of spiny dogfish (Squalus acanthias) populations in British Columbia waters. Mechanisms for density-dependent regulation of abundance were evaluated on the basis of theoretical effectiveness and ability to predict observed patterns in simulations of the historical fishery. Compensatory change in the rate of natural mortality appears to be the principal mechanism for density-dependent response. The instantaneous rate of natural mortality at natural equilibrium was estimated to be 0.094 MSY for British Columbia waters is ~ 9000–11 000 t/yr. The minimum size at entry to the fishery has little effect on MSY. Sustained-effort, sustained-yield, and periodic fisheries were modeled to determine optimum harvesting strategies. Periodic fisheries were found to vary widely in feasibility and appear to be impractical from a management perspective whereas a sustained-effort fishery would ensure maximum stability.Key words: spiny dogfish, population dynamics, age-structure model, density-dependence, simulation model, commercial fishing strategies

ISSN:0706-652X    

DOI:10.1139/f79-094

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Observations of phytoplankton production, abundance, and distribution were made at 16 stations in the Strait of Georgia from 1975 to 1977. The discharge of turbid Fraser River water exerts a strong influence on phytoplankton production and distribution in surface waters by rapid light attenuation and horizontal advection. At plume boundaries and back eddies where light conditions improve, very high production occurs (> 4–5 g C∙m−2∙d−1), because of rapidly replenished nutrients supplied by the Fraser River. Advection, turbulence, zooplankton grazing, and summer nitrate depletion collectively impart a heterogeneous distribution pattern to phytoplankton in the surface waters of the Strait of Georgia. Mean annual production varies from lows of 150 g C∙m−2in Fraser River plume to highs of over 500 g C∙m−2in sheltered boundary waters of inlets. Recent increases in ammonia and nitrate from land drainage and domestic sewage, mainly through the Fraser River, are related to increases in phytoplankton standing stocks in the Strait.Key words: phytoplankton, primary production, eutrophication, coastal marine, phytoplankton distribution and succession, chlorophylla,

ISSN:0706-652X    

DOI:10.1139/f79-095

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Hurricane Beulah (July 1975) and a major storm both caused catastrophic mortalities among intertidal benthos of the Minas Basin. In both events, surface sediment was scoured off the flats, resulting in high mortalities in shallow-burrowing organisms. The storm was a more severe catastrophe than the hurricane. The demonstrated high secondary productivity of these flats is difficult to reconcile with these observations; extensive lateral migration of the benthos may aid in recovery from catastrophes.Key words: benthos, intertidal productivity, Bay of Fundy, tidal power, catastrophes,Macoma balthica,Corophium volutator

ISSN:0706-652X    

DOI:10.1139/f79-096

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Weight, fork length, and white muscle mercury concentrations of walleye (Stizostedion vitreum vitreum), northern pike (Esox lucius), and lake whitefish (Coregonus clupeaformis) from Ball Lake, northwestern Ontario, were compared for 1971, 1972, and 1976. The lake had received mercury from 1962 to 1970; since then there have been increasingly rigorous controls. Adjusted mean white muscle mercury concentrations for walleye at the group mean length of 444 mm were 1.99, 2.71, and 1.39 mg/kg, respectively, for the three sample years. Corresponding values for pike 594 mm long were 5.05, 5.72, and 1.80 mg/kg. Whitefish values for 1972 and 1976 were 0.62 and 0.42 at 441 mm fork length. The changes are discussed in relation to the decreased input of mercury to the lake and it is suggested that mercury in suspension may be a controlling factor.Key words: mercury contamination, walleye, pike, whitefish, Ball Lake

ISSN:0706-652X    

DOI:10.1139/f79-097

出版商:NRC Research Press    

年代:1979

数据来源: NRC